A massive internal battle in the SNP is set to erupt after Nicola Sturgeon announced her shock resignation.

The Holyrood veteran has led the party for eight years - making her the longest serving and first female First Minister since the creation of the Scottish Parliament.

She had been seen as a safe pair of hands for much of that time, leading the SNP to repeated election victories at UK, Scottish and local level.

But she has been mired in controversy in recent months over gender reforms blocked by Westminster and the housing of transgender prisoners.

The move threatens to unsettle the party, Kate Forbes emerging as frontrunner for the job.

Polling by PanelbasePolitical suggests more than two thirds of Scottish voters don't know who should take Ms Sturgeon's place at the helm.

Here The Telegraph takes a look at some of her possible successors.

Kate Forbes

Often touted as a potential successor to Ms Sturgeon, up-and-coming MSP Kate Forbes has recently been on leave from her role as Cabinet Secretary for Finance and Economy following the birth of her daughter, Naomi.

A practising Christian, she has previously noted “politics will pass” while her faith is forever.

Ms Forbes is a member of the Free Church of Scotland, which conforms to a strict interpretation of the Bible, and was rumoured to be sceptical of Scotland’s gender reforms that were blocked by the UK Government.

John Swinney

Perhaps among the most obvious candidates is Ms Sturgeon’s deputy, John Swinney, the Cabinet member for Covid Recovery.

He may be viewed as the sensible choice - even if only in the interim - given his prior experience in the role - having headed up the party, then making him leader of the opposition, from 2000 to 2004.

A member of the SNP since 1979 and an MSP since 1999, he has covered for Ms Forbes during her maternity leave.

Angus Robertson

One of the most familiar faces in the SNP, Angus Robertson was the party’s leader in the House of Commons from 2007 to 2017, serving under both Alex Salmond and Ms Sturgeon.

He headed to Holyrood as MSP for Edinburgh Central in 2021, and remains a senior figure in the party, now holding the Cabinet post of Secretary for the Constitution, External Affairs and Culture.

Stephen Flynn

Whoever replaces Nicola Sturgeon will almost certainly need to be in Holyrood already, meaning it is very unlikely the party’s new Westminster leader will fill the post.

But he is worth noting as a significant figure in the SNP, having replaced Ian Blackford in the role in December last year.

Humza Yousaf

Another potential candidate is the current Health and Social Care Secretary, Humza Yousaf.

Mr Yousaf was appointed in May 2021 and was the youngest MSP elected to the Scottish Parliament at age 26.

He has served in numerous roles and in 2018, he was appointed as Cabinet Secretary for Justice. He introduced the Hate Crime Bill, which caused controversy among opposition parties.